Open Relationship

So my husband just asked my about having an open relationship. I thought he was kidding and said yea you wish and he sure did say straight up he did wish. We have been married for 7 years and are just starting to get better with our relationship after I caught him cheating. I thought he had changed and I stayed because I love him and wanted to make it work for us and our three kids. Now he brings this up and it hurts me and I’m starting to think he truly doesn’t want to be with me. I told him how I felt and he says he loves me and would never cheat on me but he wants a open relationship what is that about!?! I’m so confused and don’t know how I feel. Am I not good enough for him if he wants to do that.?